Re: Historical Perspective: Bisphenol A and Phthalates: How Environmental Chemicals Are Reshaping Toxicology

In the above-referenced publication, Drs Warner and Flaws presented a summary of the history of research on BPA and phthalates and their views on how findings from studies on these compounds have impacted the field of toxicology. There is a rich scientific literature on these substances and many of the views they presented touch on very complex issues that are topics of debate in the scientific community. We wish to provide some comments on specific points made in the Perspective.

Warner and Flaws stated that “Data from another branch of the [CLARITY-BPA] study performed solely at the FDA under GLP have not been peer reviewed yet, but preliminary data show some low dose effects that the FDA has dismissed as ‘minimal’”. However, a public peer review of the draft NTP report on the CLARITY-BPA core study was hosted by the National Institute of Environmental Health Sciences (NIEHS) on April 26, 2018 and all materials related to that meeting were made publicly available soon after (NTP 2018a,b). As with other NTP reports, the CLARITY-BPA core study report discusses the statistical evaluations used and the factors considered in evaluating the biological plausibility of statistically significant observations. The panel of external subject matter experts convened by the NTP made comments and suggestions regarding the presentation and discussion of the data, but largely supported the overall conclusions (NTP, 2018a). The final, peer-reviewed NTP research report on the CLARITY-BPA core study was released to the public on September 28, 2018 (NTP, 2018c), and concluded that the core study data did not provide evidence for biologically plausible BPA-induced lesions, particularly below the highest dose tested (25 000 µg BPA/kg body weight/day). Although Warner and Flaws may disagree with the interpretation of the data presented in the peer-reviewed NTP report, they should have been aware of the complete and transparent review of the report.

Warner and Flaws (2018) stated that “the estimated half-life of both BPA and phthalate metabolites in the human body is on the order of days.” However, they appear to be unaware of results from several controlled human oral dosing studies with deuterated BPA that indicate BPA and metabolites are eliminated with a half-life of hours and that there is quantitative elimination in the urine within 24 h (Teeguarden et al., 2015; Thayer et al., 2015; Volkel et al., 2002, 2005). Finally, Warner and Flaws also stated that “the metabolites are the true toxic agents,” but while data support this claim for phthalates, this is not the case for BPA.

DECLARATION OF CONFLICTING INTERESTS

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

REFERENCES

Available as a Supplementary File.

Footnotes